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PostPosted: 16 Jul 2010, 09:47 
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Have our readers ever run into the situation that the power iron can get very hot even if the amp is not operating at high volumes at all ?

The first thing comes into our mind can be the power transformer is shorting?

But if the overheating comes & goes. Or if the overheating temp is not constant, & goes up & down.
This tells us it may not be the power iron shorting. So what makes the power irons getting very very hot if not internal shortinng?

I want you guys do some thinking before I give you the answer.

c-J

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PostPosted: 16 Jul 2010, 12:04 
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This is due to :

1. Losses in the energy used to magnetize the iron core of the transformer.
2. Losses in the electical conduction of copper as copper is not a perfect conductor.
3. Using a tranny in a poorly ventilated enclosure.
4. Using a tranny rated at 4 A in a circuit that draws 3.9A constantly. (incorrect selection of the tranny for it's intended usage)

Pls feel free to correct any wrong info...

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PostPosted: 16 Jul 2010, 13:36 
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dtsup1 wrote:
4. Using a tranny rated at 4 A in a circuit that draws 3.9A constantly. (incorrect selection of the tranny for it's intended usage)

This would be my guess in most cases, my 25EH5 amplifiers power transformer gets quite hot after a couple hours of use, and it is not really all that consistent of a heat either. Even if I have the HV off it still gets just as hot and there is only about 1.5 amps draw at 6.3 VAC when the HV is off.

It makes me uneasy sometimes just how hot it gets, but that is the way it is and as long as it doesn't produce any burning odors I am happy. :D

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PostPosted: 16 Jul 2010, 14:25 
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I guess ur transformers are the EI type.
Have you noticed any Toriods getting that hot?

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PostPosted: 16 Jul 2010, 14:37 
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dtsup1 wrote:
guess ur transformers are the EI type.

Hi.

This overheating problem can happen to any build of power irons., EI or torroidal.
dtsup1 wrote:
Have you noticed any Toriods getting that hot?

Yes, in fact toroids can get even much much hotter than EIs for the same situation I want to discuss with you guys.

c-J

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PostPosted: 16 Jul 2010, 14:46 
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dtsup1 wrote:
This is due to :

1. Losses in the energy used to magnetize the iron core of the transformer.
2. Losses in the electical conduction of copper as copper is not a perfect conductor.
3. Using a tranny in a poorly ventilated enclosure.
4. Using a tranny rated at 4 A in a circuit that draws 3.9A constantly. (incorrect selection of the tranny for it's intended usage)

Hi.

No, you are on the wrong wavelength.

Such overheating problem can occur to any NORMAL functioning power irons, torroids or EIs, of any rating or even overrating.

Hints: this is something overloading a switched on power iron. It got nothing to do with the iron rating or its misfunctioning at all.

c-J

PS: This is something that can happen anytime any where as long as the amp is switched on, with or without load.

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PostPosted: 16 Jul 2010, 15:17 
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Got no idea at all! Let's wait for more responses..

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PostPosted: 16 Jul 2010, 15:37 
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dtsup1 wrote:
Got no idea at all

Hi.

Here is the direction to go for:- why a transformer, O/P or power, cannot be used as DC filter choke?

c-J

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PostPosted: 16 Jul 2010, 15:56 
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cheap-Jack wrote:
Here is the direction to go for:- why a transformer, O/P or power, cannot be used as DC filter choke?

Saturation of the coil due to no air gap in the windings?
So are you saying that the transformer when idle (no power drained), behaves like a choke?

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PostPosted: 16 Jul 2010, 17:16 
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Radiation from nearby tubes can also add to the problem.

It is not that unusual to have a small DC offset on your AC mains power. Just a little bit of DC can cause significant heating. "Dimmers" like on a lamp, or in hot air gun or a computer psu on the same circuit can be the cause of the problem.

DC on the mains also increases mechanical noise, in particular with torroids.
Cheers

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